Twitter is a free microblogging meets social networking site where users post short, 140 character updates or "tweets" ranging from "what I'm doing right now" status updates to sharing links to light conversation with friends and colleagues. One of the key features of Twitter is the ability to update from an almost "source agnostic" array of devices including directly from the website, from various desktop clients on multiple platforms, via SMS, from email, from Facebook, and via other third party apps and gateways.

Started as an internal application in the Odeo offices (a San Francisco podcasting startup founded by Evan Williams and Biz Stone of Blogger fame) in early 2006, Twitter was released to the public in October of that year and began gaining widespread popularity after being adopted by an influential set of alpha geeks at the South by Southwest conference in Austin, TX in Match, 2007. Reports estimate between 3 and 5 million users of the service as of December 2008.

Written in Ruby on Rails, Twitter has experienced its share of growing pains as it scaled up to accomodate a growing amount of traffic, particularly during peak events. Twitter outages were commonplace during a large chunk of mid-2008, spawning the popular "fail whale" internet meme based on the iconic "website is down" message the service would display when over capacity. Fans of the service went as far as to create a fan club and Zazzle store to commemorate the dreaded/loved Twitter Fail Whale.